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Key Points on Organelles I – “Manufacturing and
Shipping”:
1. Nucleus
a. The control center of the cell that contains instructions for how a cell
operates, DNA.
b. Separated from the rest of the cell by the nuclear membrane.
i. Selectively permeable, meaning it only lets certain substances in
and out.
ii. Substances pass through nuclear pore complexes (NPCs).
c. Transcription occurs here, producing RNA, which will be transported
out of the nucleus.
2. Ribosomes
a. Two subunits, or pieces, that a strand of RNA can fit in between. Found
all over the cell.
b. Perform translation, producing proteins from RNA.
3. Endoplasmic Reticulum
a. Flattened sacs that are connected to each other and also to the
nucleus.
b. Two types, rough and smooth. Rough endoplasmic reticulum (RER) has
ribosomes attached to its walls while smooth (SER) does not.
c. Proteins and other substances are produced in the endoplasmic
reticulum.
i. It also allows proteins to fold into the correct shape.
4. Golgi Apparatus
a. Flattened sacs that are not connected.
b. Gathers simple molecules and combines them to make molecules
that are more complex. It then takes those big molecules, packages
them in vesicles, and either stores them for later use or sends them out
of the cell.
i. Vesicles are small sacs that can move around the cell
transporting substances.
ii. Proteins produced in the RER can be sent to the Golgi with a
vesicle.
Key Points on Organelles II – “Support System”:
5. Cytoskeleton
a. A system of long rigid protein strands that provide support to the cell and
determine its shape.
b. Organelles can be moved around the cell by the cytoskeleton.
c. Structures that help the entire cell move called flagella (a long tail-like
structure) and cilia (shorter, hair-like material) are considered part of the
cytoskeleton.
6. Centriole
a. A barrel –shaped structure made from a cytoskeleton protein. Each
animal cell usually has two centrioles.
b. Functions during cell division (mitosis) to pull the two copies of DNA to
opposite ends of the cell during metaphase.
7. Cytosol
a. A gel-like substance that fills the inside of the cell.
b. It is made up of water, salts, and many other molecules that serve a
purpose in the cell like fats and starches. Most of the cytosol is water.
i. Since these substances are dissolved in the cytosol, they can
move throughout the cell.
c. Organelles float in the cytosol, allowing the cytoskeleton to move
them easily.
8. Lysosome
a. A modified vesicle that contains acidic substances.
b. Break down proteins and organelles that are old or no longer needed,
food particles, bacteria, and viruses.
c. If a cell becomes very damaged, lysosomes will break open and
destroy the entire cell. Sometimes lysosomes are called “suicide-sacs”
because of this.
Key Points on Organelles III – “Energy, Plants, and
Animals”:
9. Mitochondria
a. Power plant of the cell. Cellular respiration occurs in mitochondria. Glucose is
oxidized, releasing carbon dioxoide and water. Found in both plant and
animal cells.
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
b. Cellular respiration produces ATP, adenosine triphosphate, which is used all
over the cell to provide energy.
c. Mitochondria look like small bacteria and have a double membrane, two
walls, that surround them. These two walls allow them to complete the
process of cellular respiration.
d. The number of mitochondria in a cell depends on the type of cell. Cells that
move with a flagella require many mitochondria while others that are
stationary do not require as many.
10. Cholorplasts
a. Location of photosynthesis which produces glucose for a cell by reacting
carbon dioxide and water to form glucose and oxygen. Found only in plant
cells.
6 CO2 + 6 H2O → C6H12O6 + 6 O2
b. The glucose produced by photosynthesis can be broken down in
mitochondria to release ATP.
c. Chloroplasts have a double membrane. Inside are flat discs stacked
on each other, called thylakoid membranes, are where photosynthesis
occurs.
d. Cholorophyll which absorbs blue and red light but reflects green
wavelengths of light, is found in the thylakoids.
11. Cell Membrane
a. Structure that forms the outside boundary of the cell. Made up lipids
(fat) and proteins. Found in both plant and animal cells.
b. Selectivity permeable, meaning that only certain substances are
allowed in and out of the cell.
12. Cell Wall
a. Found outside of the cell membrane only in plant cells. Provides the
cell with support and protection.
13. Vacuole
a. A large organelle found only in plant cells that contains water.